We have investigated the postnatal migration and integration of several cerebellocortical neuronal types, based on detailed spatio-temporal analysis of the distribution of the different neuronal populations. We concluded, that about one third of the Purkinje cells, the Lugaro cells, the unipolar brush cells as well as the interneurons of the molecular layer occupy their place in the cerebellocortical cytoarchitectonics during a prolonged perinatal-postnatal developmental period, which is characteristic of the given neuron.
The postnatal build up of the cerebellar cortex is rather sensitive to different endogenous or exogenous noxas, and can be disturbed by systemic application of 5-bromo-2'- deoxyuridine (BrdU). Postnatal BrdU treatment by 50 ug/g b.w. BrdU for 6 and 12 days after birth results in the retardation of somatic and neuronal developmnet in C57Bl6 mice. Dose dependent proportion of granule cells is going to die, high number of the Purkinje cells remain in ectopic position and many more are not able to align into the ganglionic monolayer. Postnatal migration of cerebellar granule cells and the interneurons of the molecular layer are also disturbed. The morphological damage of the cerebellar cortex is followed by a disturbed movement-coordination. Postnatal BrdU application, in a lesser extent, results in the retardation of the development of somatosensory cortex too, followed by increased hyperexcitability and enhanced seizure susceptibility.